This invention relates generally to pressure responsive switches and deals more particularly with a switch device which is sensitive to a pressure differential between low and high sides of a fluid system.
Various types of fluid systems are equipped with switches that are actuated when there is an excessive pressure differential between two parts of the system. Although existing switches of this type have functioned well for the most part, they have not been wholly without problems. The useful life of some existing pressure differential switches is relatively short, particularly for switches used in high pressure service and those subjected to transient shock or spike loads. Some devices must be connected in one particular orientation to the high and low pressures and can be severely damaged if connected in a reverse fashion. When the pressures to which the switch is exposed vary over a wide range, it is difficult to accurately maintain the differential set point, and the sensitivity of the device suffers accordingly. Another serious problem has been to prevent deterioration of the components of the switch when corrosive fluids are being handled.
Existing switch devices are usually arranged such that the pressure sensitive components travel a relatively long distance in order to assure proper actuation of the switch when the set differential pressure is exceeded. This long travel increases the wear on the various parts, particularly where seal elements and/or linkages are employed. Additionally, in some cases it is difficult if not impossible to vary the set point of existing devices while they are in service under pressure.
The present invention is directed to an improved pressure differential switch and has, as its primary object, the provision of a switch device which is capable of functioning effectively over a wide range of pressures and a wide range of pressure differentials. The device is constructed to withstand pressures up to approximately 3,000 psi with either port connected with the high pressure side of the system. The unit is also constructed in modular fashion so that the components can be changed to permit a wide variation in the differential set point and to accomodate pressures up to 10,000 psi.
Another important object of the invention is to provide a switch device of the character described which can readily absorb severe transient shock loads without damage.
Yet another important object of the invention is to provide a switch device of the character described in which the travel of the pressure responsive components is limited without adversely affecting proper actuation of the switch.
A further object of the invention is to provide a switch device of the character described wherein the pressurized fluid medium is isolated from the critical components of the unit so that corrosive fluids can be readily handled.
A still further object of the invention is to provide a switch device of the character described which may be quickly and easily assembled and disassembled and which presents no danger from excessive pressure buildup.
Other and further objects of the invention, together with the features of novelty appurtenant thereto, will appear in the course of the following description.